Immune
by prettysupervampz
Summary: Sam and Dean Winchester and their sister Layla are unexpectedly thrown into the zombie apocalypse. Layla wants to find her ex Glenn Rhee. But Dean pushes towards the CDC. When the Impala breaks down and all hope seems lost, one person will save the day: Glenn. And now, the now feuding siblings must put aside their problems as they join those in the prison and fight to survive.
1. Chapter 1

**Hello, all. Well I've been using Wattpad a lot and figured I might as well start publishing on here to. So, I'm starting with my newest fanfiction. I've thought up this crossover. It's set between season 3 and 4 of The Walking Dead and post season 8 of Supernatural. Now my main character is of my own creation, and to make things interesting, I decided "Hey, why not make her a vampire?" So I'm using the Vampire Diaries to make her a vampire. However, the characters from TVD will not be in the story. They may be mentioned but not actually a part of the plot. So, here's chapter 1 of Immune. Enjoy!**

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><p><strong>Chapter 1<strong>

At the sound of gunshots, Layla manages to peel her eyes open, her hand automatically snatching up her sleek black bow from beside her pillow. She snatches up her sheath of silver-tipped arrows and slings it across her back, pulling out and quivering an arrow and aiming it at the front door of the abandoned cabin. She glances over to the armchairs in the corner, finding that her brothers no longer occupied them. Where could they have gone? Almost immediately, the cabin door swings open, Sam and Dean emerging quickly before shutting and locking the door back. Sam slips into the back of the cabin and Layla sighs softly.

"Time to go?" she asks Dean, who quickly starts to gather what few things they had with them.

"Layla, head's up," Sam's voice calls from behind her as he tosses her a shotgun. Her advanced reflexes work before her mind does, the bow and arrow on the bed and the shotgun in her hands before she can fully register her own actions.

"Croates?" Layla asks as she loads her shotgun. The loading of the other guns around her is answer enough. "Awesome," she mutters in the dry sarcasm that Dean typically used. "How many"

"Dozen," Sam answers, loading his Baretta and placing it in his waistband before grabbing a nearby machete. "Maybe two. Can't tell."

"Dean," she says, turning to her older brother. "I'll take the front, you and Sam flank me." Dean lets out a humourless laugh.

"Don't think so," he says sternly. "I'm not letting you get hurt." Layla scoffs lightly.

"I can't be turned, remember? This conversation is over. Let's go."

"Layla." Dean grabs her wrist as she pushes past him and she easily snatches her arm free. Dean reaches again and she blurs to the nearest wall, taking him with her and pinning him to the wall. Faintly she can hear her younger brother cock his gun.

"Layla," Sam warns. Layla faces him, feeling the veins darken below her eyes. "Stand down."

"I'll take the front," she repeats lowly, releasing Dean and picking up her dropped shotgun. "_Let's go_."

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><p>"Here," Sam says as he approaches Layla, offering her a clean towel.<p>

"Thanks," she mumbles, taking the towel and removing the old one from her shoulder, the raw flesh beneath over halfway healed. "It'll probably be another hour or two before the fever hits." Sam nods and checks the bite before she places the towel onto it, groaning softly. "Sorry about earlier," she says to Dean, looking up at him and watching him clean their weapons.

"It's fine," he mutters, though apparently only she recognises it as a lie. "I keep forgetting not to piss you off." Layla walks over to him and kneels down in front of him.

"We gonna talk about it?" She asks gently.

"About what?"

"You know what." She puts a hand on his and he stands, freeing his hand and approaching the motel bathroom. Dean spins around, anger and frustration clear on his face.

"What do you want me to say, Layla?" he half-shouts. "Am I supposed to be happy that you're-"

"It's the damn apocalypse, Dean," Sam interrupts.

"Is that supposed to make it better?" Dean takes a few steps toward his younger siblings. Layla keeps her silence, almost afraid to speak and anger him further.

"She's our sister," Sam says calmly.

"She's not _human_!" Dean snaps. He huffs in exasperation and takes another step.

"She's still family."

"Doesn't change anything," Dean says in a quieter tone. "She's still a vampire." Once the word hits the open air, an uneasy silence arises. Layla stands and faces Dean, finally deciding to speak up.

"I know you don't like what I am, Dean, but I can't change it. You might as well get used to it." Dean folds his arms over his chest and keeps his eyes trained on the floor. "Or," she continues, "you can let me leave."

"No," he says quickly, his eyes snapping up to meet hers.

"Then get over your prejudice against vampires. I'm not gonna hurt anyone."

"Like you 'didn't hurt' that Elena girl?" Layla's face hardens.

"I wasn't in control then," she says with a sigh.

"But you are now?"

"Yes!" she exclaims, throwing her hands up in exasperation. "I haven't had human blood in _months_. And if I wasn't a vampire, I would've died last month when that Croate bit me."

"You _did_ die!"

"But I came back!" she points out. "And not as one of those... things."

"Croatoans," Sam supplies.

"Are you _sure_ they're Croates?" she asks, turning to her younger brother. "They're not like the ones we dealt with in Oregon. Those were more aggressive... full of rage. But these..."

"They're Croates," Dean says, silencing the room from that point on.

The siblings spent the next morning packing and fighting their way out of the abandoned motel, losing count of how many corpses they'd killed going from the room they'd claimed to Dean's 1967 Chevy Impala. Despite being a vampire, the zombie bite still affected Layla. She lasted long enough to get into the car before blacking out. She'd been bitten before. She always got the fever. She always died. But she never turned. She was immune. But then again, she was technically already dead.

Dean pulls onto the interstate no more than five minutes after leaving the motel. They'd dodged the main road two days prior after spotting several dozen Croates, or whatever they really were, filing through the abandoned cars. Sam and Layla both felt that they should steer clear of highways and main roads, keeping to backroads until they neared the CDC. But Dean... For some reason Dean felt the need to follow the bigger roadways. Maybe he was searching for other survivors or a large space the three of them could be safe.

Little did they know that they'd soon have both.

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><p><strong>AN: TA-DA! Immune. Now for some readers this chapter might not make sense. If so, DON'T WORRY. I _will_ explain anything and everything that needs explaining. :) Anyway, I should have chapter 2 up soon and I hope you enjoy! The second chapter should be longer and will have more Walking Dead in it.**

**-B**


	2. Chapter 2

**Alright I know it's been a while but I have had absolutely NO time to write. I barely have any time now, to be honest. But I really wanted to get chapter 2 out and I have some fresh ideas so here it goes!**

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><p>Chapter 2<p>

Nobody ever asked what the virus _felt_ like. Maybe it's because no one wanted to talk about it or no one besides Layla could live to tell the tale. Everyone knew what the virus looked like. And everyone could guess at how it felt... But only Layla knew. This was her fourth time dealing with it. And it never got any easier.

"Layla, please. Just relax," she hears Sam tell her. His voice was gentle and worried, as it was each time. And it sounded so distant.

"You try to relax when you're in this kind of pain," she mutters sharply, her voice cracked and hoarse. Her head rested in her brother's lap in the backseat as Dean drove.

"Not like you haven't dealt with it before," Dean says absently, his eyes scanning the road as he drives slowly down the crowded highway, maneuvering carefully through the abandoned cars. Layla groans and glares at her older brother, her hand clutching her side.

"Oh, screw you," she says between clenched teeth before coughing roughly, only making her throat burn more than it already did. Sam pulls out fresh gauze and removes the old ones on Layla's neck, grimacing faintly at the sight. Layla laughs painfully. "Suck it up, little brother. I know you've seen worse."

"I know," Sam says sadly. "I just don't like seeing you in pain."

"Well, get over it." Layla coughs again violently, her hand flying to her mouth. She sighs weakly when she draws her hand back, frowning at the red in her palm. "Almost time," she wheezes, looking up at Sam.

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><p>"She's out," Sam says as he climbs into the passenger seat, his sad eyes watching his sister's motionless form. It was easier for him to make it sound like she was asleep and not dead again. Dean pulls the car over, earning a frown from Sam. "What's going on?" Dean holds up a silencing finger and lowers the car window slightly, listening intently. He smiles softly and pulls off into the highway again. "What was that all about?" Dean glances at his younger brother.<p>

"I heard people." Sam raises his brows. "Which means there might be a group nearby."

"Need I remind you that our sister is dead in the back seat?" Sam asks with a somewhat concerned look on his face. "How do you expect to explain that?"

"We can wait until she wakes up. Shouldn't be but another 10, 15 minutes at least." Sam shakes his head lightly.

"Fine. But we wait." Sam glances into the back seat again and sighs at the body of his sister.

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><p>A deep gasp rose from Layla as she sits straight up in the back seat, her green eyes wide. It was the exact same way she woke up every time after she died. Sam, still seated in the passenger seat, jumps slightly and looks back at Layla.<p>

"You're awake," he observes softly. "Good." Layla nods, breathing deeply and raking a hand through her hair, frowning as her fingers refuse to comb through. She looks in the rearview mirror and her frown deepens at her reflection. At her blonde hair matted with dried blood. At her cracked lips, a sickly purple blue in colour. At her pale skin, slowly lightening again. At the old bite that was mostly done healing, but it was still clear what it was. She trails her fingertips over the wound.

"For once," she says in a voice so hoarse that she barely recognised it," I _actually_ look dead." She glances at the driver's seat, creasing her brows at the sight of the empty leather. "Where's Dean?" she asks concerned, her eyes flitting back to her younger brother.

"Routine check," he says simply. And Dean happened at that moment to climb into the car. Layla tenses and narrows her eyes as the scent of blood washes over her. _So Dean was hurt. Great._ She steps out of the Impala and slams the door so hard that the window shatters. Dean gets out with a scowl on his face.

"What the hell, Layla?" he growls angrily, looking at where the window was before.

"You managed to get yourself hurt on a routine check?"

"Not all of us heal as fast as you do," Dean says bitterly, earning a glare from Layla's darkening eyes. Before she could utter a retort, the sound of approaching Croates meets their ears. In a moment, Dean and Layla had their weapons drawn, poised at the group finally coming into view. "Good job, Layla. You brought the Croates." Dean pats the roof of the Impala and Sam climbs out, gun raised in the opposite direction. Layla looks around.

"Dean, we're surrounded," she says, looking from one dead face to another. She holds her dagger sideways in a battle-ready stance. She takes a hesitant step forward and glances back at Dean. She turns back and rams the blade into the left temple of the Croate and twists before yanking the dagger back out, blood sputtering from the wound. The Croate crumples to the ground but Layla had already driven her blade into the skull of another.

The sound of tires screeching resounds as a green vehicle swings into view, coming to a halt just before the Winchesters. The passenger door swings open and Layla's breath catches.

"Glenn?" she breathes with widened eyes as she stares at the familiar face.

"Get in!" Glenn orders, eyeing the approaching herd of Croates. "Sam, Dean! Follow me!" Layla clambers into the car and slams the door as Glenn speeds away, Dean and Sam close behind in the Impala.

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><p><strong>AN: So sorry it took me so long to post an update! I have been super busy and am just now having the time to post. I know its short but I needed to put a fresh piece out. I will try and get more, A LOT MORE, written AS SOON AS POSSIBLE. Enjoy! And please leave a review!**

**-B**


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